1. Field of the Invention
The present invention relates to a liquid-type image forming apparatus having a carrier vapor-processing device for processing carrier vapors occurring when a printing operating is performed, and a method of controlling the apparatus.
2. Description of the Related Art
Generally, a liquid-type image forming apparatus forms an electrostatic latent image by illuminating a laser beam to an image carrying medium, such as a photosensitive drum. A visible image formed by attaching a developer to the electrostatic latent image is transferred to a sheet so that a desired image can be obtained. Such an image forming apparatus is suitable for color printing because a clearer image can be obtained compared to a dry-type image forming apparatus using a powder toner.
FIG. 1 schematically shows a structure of a conventional liquid-type image forming apparatus.
As shown in FIG. 1, the conventional liquid-type electrophotographic image forming apparatus 10 includes a main body 11 of the apparatus, a plurality of photosensitive drums 12, 13, 14 and 15 on which electrostatic latent images are formed, a plurality of electrification devices 22, 23, 24 and 25 for electrifying each of the photosensitive drums 12, 13, 14 and 15 to a predetermined electric potential, a plurality of exposure devices 32, 33, 34 and 35 for illuminating a laser beam to each of the electrified photosensitive drums 12, 13, 14 and 15, a plurality of developing units 52, 53, 54 and 55 for supplying a developer to each of the photosensitive drums 12, 13, 14 and 15 for forming visible images, a plurality of first transfer rollers 62, 63, 64 and 65 for transferring the visible images formed on each of the photosensitive drums 12, 13, 14 and 15 to a transfer belt 60, a second transfer roller 66 transferring a final image that is formed on the transfer belt 60 by the visible images being superposed thereon to a supplied paper P, and a fixing member 70 for fixing the final image on the paper P by applying heat and pressure.
The plurality of developing units 52, 53, 54 and 55 respectively store developers of different colors, and supply the color developers to each of the photosensitive drums 12, 13, 14 and 15. The developer consists of ink having toners dispersed therein and a liquid carrier such as norpar. The norpar is a hydrocarbon solvent that is a mixture of C10H22, C11H24, C12H26 and C13H28. The developers attached to each of the photosensitive drums 12, 13, 14 and 15 for forming the visible images are transferred to the transfer belt 60 and superposed thereon. The final image formed by the plurality of visible images superposed on the transfer belt 60 is transferred to the supplied paper P. When the paper P passes through the fixing member 70, the ink component of the developer is fixed to the paper P. The liquid carrier of the developer is evaporated to an inflammable hydrocarbon gas, such as methane (CH4), due to the high temperature.
The inflammable hydrocarbon gas, which is classified as a volatile organic compound (VOC), pollutes the environment and emits offensive smells when being discharged. Due to such problems, diverse methods for removing the inflammable hydrocarbon gas have been currently provided.
The currently known methods of removing the inflammable hydrocarbon gas includes a filtering method of physically removing the gas component using a carbon filter, such as activated carbon, a direct combustion method of combusting the gas component at an ignition temperature (600˜800° C.), and an oxidation catalyst method of combusting the gas component at a relatively low temperature (150˜400° C.) using a catalyst and thus oxidizing it into water and carbon dioxide.
In the filter method, the carbon filter has no capability of decomposing the carrier collected therein. Accordingly, the filter method has a disadvantage that when the carrier is collected beyond a predetermined amount, the saturated carbon filter needs to be replaced. The direct combustion method has a safety problem due to the high temperature.
Owing to the above-mentioned problems, the oxidation catalyst method is mainly used in recent years to remove the carrier vapor in the liquid-type electrophotographic image forming apparatus. Additionally, there is an increased interest in improving the efficiency of oxidation of the carrier vapors.
Accordingly, a need exists for an improved liquid-type image forming apparatus that efficiently processes carrier vapors occurring during printing operations.